When I sailed in December, I went to hotwire and they offered a four star property - I looked for a downtown site....I got one listed for $104. It turned out to be the Miami Intercontinental, a mile from the port - the rates the day we checked in were $339! Very luxurious. No shuttle to the port but the cab was under $10. Many times I stay at the Extended Stay - it is not fancy but serviceable - they have just remodeled it, however. The plus to that is that one of my favorite restaurants ANYWHERE in the world is Tutto Pasta, a block down the street. I've written a review about the place on www.yelp.com.
which includes photos. I fly in a day early and plan a late flight home to maximize my eating there.
Believe me, the food is worth a cab ride, regardless of where you are staying. It isn't far from the port and they have an incredible menu and the desserts, especially the passion fruit mousse are to die for. It isn't open on Sunday, though. The chef/owner, is from Brazil - go figure, an Italian restaurant, but he is fabulous and has become a friend. I have sent so many people there over the years and Captain Hakan from the Brilliance said he will dine there when he overnights in Miami!